A simplified process of swine slurry treatment by primary filtration and Haematococcus pluvialis culture to produce low cost astaxanthin

A simplified process for treating swine slurry through primary filtration and subsequent depuration of thefiltrate with the astaxanthin-rich microalga Haematococcus pluvialis is proposed. The first step comprisesa low-cost filtration system capable of reducing 66% of ammonia, 7% of phosphorus and 19% of chemicaloxygen demand, and increasing the concentration of nitrate, being this useful for subsequent growthof the algae. The second step comprises the discontinuous cultivation of H. pluvialis in diluted filteredslurry. The optimal dilution was researched by testing undiluted and 2, 4 and 8-fold diluted filtrate. Thisstep led to a drastic reduction in macro and micronutrients concentration (up to 99% for NO3-N andNH4-N, 98% for TP and 26% for chemical oxygen demand). After H. pluvialis growth the accumulation ofastaxanthin took place for 14 d in nutrient-deprived conditions: an astaxanthin accumulation of 1.27%on a dry weight basis was measured. These results indicate the possibility to couple low-cost filtrationand microalgae production to recover nutrients from swine wastewaters and to add value by producingvaluable astaxanthin for the feed market or for an on-farm utilization as feed addictive.